Telephone-exchange system.



A. B: SPERRYQ TELEPHONE EXCHANGE SYSTEM.

APPLICATIONUILED MAY I 1916- I PatentedApr. 3, 1917.

4 SHEETS- SHEEI I.

I In yen/or.- A m h ur B, Spar/"y.

A. a SPERRY.

" TELEPHONE EXCHANGE SYSTEM.

AP'PHCATIDN FILED MAY 1. 1916- ?ammea Apr. '3, 1917.

4 SHEETS-SHEET 2.

m/MAkY l l L 20.7

A. B. S PERR Y'. TELEPHONE EXCHANGE SYSTEM.

APPLICATION men MAY 1'. 1915. 1,221,773. Patented Apr. 3, 917.

4 shins-sneer a In van/0r- A fhur B. Sperry. b ol My multiples of such -ncna alling in the other linders in-whic'li' itappears.

' third party into the ARTHUR B. SPERRY, OF NEW YORK, N. Y.,

LSSIGNL. 'IO WESTELN ELECTRIC COMPANY,

INCORPORATED, 013 NEW YORK, Y-, A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented Apr. 3, 191".

Application filed May 1, 1916. Serial No. 94,672.

To all whom it may concern:

Be it known tliz'i't I, An'rimn B. SPnnnY, a citizen of the United States, residing at New York, in the county of New York and State of N cw York, have invented certain new and useful Improvements in Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems employing machine switchin with suhscribcrs control.

its object is to provide a circuit arrange; ment whereby a calling, party, after being connected with a called party over a'nonnumerical automaticswitch, such as a line finder. and a number of numerical switches, such as selectors and a connector, may, operating: his sender, bring a third party into the connection over another train" of automatic switches. Provision is also'm-ude for introducing another party or parties into the talking, circuit thus established, if desired. P

in the embodiment shown,the suhscril ers" lines terminate in automatic fi der switches and in connectors. moval of the receiver hy a calling party, a calling: condition is set up on the test multi ples of 'such line in the finders in which it appears. and an idle line linder is set in motion to connect with such multiples. The test hrusl'i of the finder. on reaching the calling! line test multiple,appearing closes a circuit including said multiple, which causes the finder to stop thereon, whereupon the cut-off relay of such line is energized. This relay; in attracting its armaturesi dei ncrgizes the line relay. The

line relay, in releasing itsarmatures, Eremoves the calling condition from the test line to render the same 'l'he suhscriher then sets the tor associatcd ,with such finder to pich out; a connector ha ring. access to, the called {dul tts line. which is then set upon such line. l-t'. after marvel-sing. it is desired to bring a connection. the calling! party operates his sender to transmit a num her of impulses to a switch associated with the finder connected to his line.- This switch operates in response to such impulses and cll'ects'thc dci ncrgiiza tion ot' the calling line cut-oil icl'ay. which. in releasing its armaim'es. again-closes the circuit of the line re;

selec- Upon the" retherein,

the sin-(ceding lay over the calling; line. The energization of the line relay sets up a calling condition on the calling line multiples in the finders in which such line appears, and initiates the operation of an idle line finder having access to such multiples, which connects therewith. The calling subscriber now lay means of his sender, operates the selector associated with such finder to picl: out and set a connector having access to the group containing the line of the third party, who is then signaled, if his line is idle, and is brought into the connection.

More specifically, provided fofeach tinder, which, in the pres-, ent embodiment, is a side switchcontrolled by an escapemagiet, which releases a contact arm'from position to. position npon'its deenergization in the well-known manner. It will be understood, however. that the finder is also pro rided with the usual side switch having" a plurality of arms, and

' which controls the yarlous finder operations. In the through position of the special side switch and the connector side switch, the escape magnet of this special side switch is connected" to a contact of the calling partys stepping relay. The circuit for maintaining the cut-ofl' relay of the calling line energized leads through the arm of said special side switch and its first contact. The connection to one oi the following contacts of said arm is left open. I Consequently, when the calling party operates his sender ,to transmit a given nmnher.of"imp-ulses. aft-er ha ving set up -a '(onnection; the steppingrelay operates the escape magnet of this side switch, which ad rances its arm into engage- 'ment with said open contact. whereupon the cut-oi'l' relay is decnergizede and when its armatures reach their hack contacts the line relay energizes ever the calling line circuit, vand m cnergizuin. applies v a calling condition to thc callingline multiples in the findcrs. aml starts an idle tinder in operation :to connect with multiples of such line in such 'linder to provide another pa'th o\'c-1.' which the call to thethi-rd party may he set up.

The contacts follow-in such '0 3811 contact.

are grounded so that in case a greater numher of impulses -are transin1tted.,the ari'n. aftccpassmg the open contact and reaching energizes the cut-off relay to remove the callingcondition, if such cut-01f relay denergrounded contacts, again gizes during the short interi'alin which the 107, armature and ,back contact of finder-rearm is passing 'over the open contact.

' In a modification of the invention, a series of counting relays is" associated with the finder [instead of the s ecial side switch. The circuit of the cut-o relay is controlled at an armature andback contact of the last i Y one of these relays in the string When a -'connecticn is completed, these relaysare connected to a contact of the calling partys I s'teppi relay. When the proper number cf impu ses are transmitted, the counting rewlaysare successively energized. and-locked Q-up, the ehergization of the last relay in the fries opening the circuit of the c'u-t-oif rea'y, whereupon, the line relay operates. to cause "a second finder to connect with-the calling line, Ifa smaller number of im- Fulses'are transmitted, the last counting re ay is not reached, and if a greater number,

although-the last relay is" energized and cpenstlue circuitiof the cut-ofiqrelay, the

en'erg zes such cutoff relay to again remove the, callingwcondition, ifsuch :cut-ofi' relay has-had time to deenergize. v.

: Referring to the drawings which illus' trate diagrammatically the circuit arrange ment ofthis .invention,-"Figure l'shows the line finder circuit; Fig, 2"shows the first seodifi'etl selector circuit; and Fig. 5 is a 'wbf af modified finder circuit.

tions. involved in setting up a connection.

.101j'of the calling group andenergizes attracting its right arma- .100,l-hy attracting-its left armature, I a shunt ath about cut-ofi' relay 120 to callnig'lmultiples 119. Relay byiattra V "'g its leit'armature locks to} "round independently of" relay 101,

d-lfby attracting its right armature, grounds a in-star relay 104 operates idlyat this 1 circuit for the primary stepping magnet 106' net Mature and back contact, arm

of the line *fihli": free pole of battery,

,lect or circuit; Fig. 3 showsthe connector vci eu it;;Fig. ,4 is a. view: of a portion of aheinvention will be-more clearly under-- ,from rdetailed description of the op-- relay 1Q2co'nimonto this group:

ter, wn 'e 103 and energizes relay,

' ,ne jxt, impulse operatesja'relay, which again,-

pen the ,olfemovalofthe receiver at fthecalln'g substation A, the line relay is en tiple seg lease 'inagnet 108,'left',ar1nature and back contact of relay 109, starter wire 103', to

ground-at the right armature'and front conis sliort-circuited by the path justtra'ced over finder side switch arm 107 to'g ro'und at the right armature and front contact of relay' 102.. LTheshaft is thusgiven one step by magnet 1 06, in which position the commutator brush-112 thereon engages the calling commutator segment101, and since at this moment the shunt about magnetlll is open at the armature and back contact of magnet 1.06, magnet 111 energizeifover the following circuit: free pole of battery, mag- ;nets 106, 111, left armature and jront contact of relay 110,. brush 112, segment 101,'.

right armature andfront contact of .relay 100, left armature andfront contact of rela 102 to ground. -.1\'Iagnet 111 is construct- 1 e to release the side switch arms from position 1 to. position 2, upon its 'energization. I Magnets 100, 111 remain locked up in osii tion 2 in'the following circuit: free po e of battery, magnets 106, 111, armature and back contact"of relay. 121, arm 122, side switch arm 180 to'ground. Arm ,180 does not belong to the side switch controlled by escape magnet 111, but to an escape magnet In position .2- the circuit of secondary stepping n'agnet 113 is closed drive the I brushes 114,115, 116 over the multiples of the group containing those ofpthe calling line 117 ,.l18, 119. This circuit is'as follows: free pole of battery, magnet 113, its armas ture and back contact, armature and front contact of the magnet 111, arm 10] and its I second contact, armatureand back contact of magnet 108, leftarmature and baclc cone tact of relay 109 to ground at the right armature and front contact of' relay 102. Relay 121'is margina1,andis not energized through the high resistancecut-off relays l20' of the. non-calling lines. When, "however, finder test brush 1 16 engages test contact 119 oi the callin'glline'towhichis connected the low..resistance shunt about the cut-off relay 120, relay 121 is energizeiand by attracting its armature opens the circuit of themagnet 111,, which in" denergizing" releases the side switch into position 3,-arm l 10'Z', 1n passing. out of position 2 opening the circuit, ofma 122 shunts out e a 2 grounddirectly .to cut-01f. relay 1 20 oflthe. g, cal li ng-lin e, ,which iin attracting its arma tures, denergizes lme relay 100, which in gnet 1 13. Imposition 3,'=arm.

retracting, its-left ,iarmature, removes; the;

shunt, from about; cut-wolf relay to render the line non-calling, in the finders in which it appears, and, by retracting its right armature, denergizes starting relay 102, which removes ground from the starter wire, thus deenergizing relay 110 which disconnects niagnet 111' from brush 112. The right armature of rclav' 102 in retracting reeonnects the section 139 of the in-starter ivire coming from the preceding finder to section 103. Arms 122-1, 121, in'position 3, extend'the calling line-to a stepping relay 125. which thereupon energizes. and by at tract-ing its armature, cncrgizesa slow relay 12th Relay.12l by attracting its left armature, interposes a break in the circuit of finder release magnet 108. and by attracting its right armature, energizes a slow relay 200 (Fig. 2) over arm 201 and its first contact. Relay 200, in attracting its right armature, interposes a break in the. circuit of selector releasc magnet 202. and by attracting its left armature. energizes relay 109. This relay. by attracting its left armature. extends the iii-starter Wire 103 to the out-starter wire 12? leading to the next. idle finder. The calling part now operates his sender 128. in acctualance with the first digit of the wanted number. The stepping relay 125 dei nergizesat each interruption of the circuit-but the relay 126 beingslou' to release. maintains its arlnaturcs attracted during these interruptions. lat-h time the armature of relay 125 is rctractcdcan impulse is sent to primary stepping magnet 203 of the first selector. over the following path; arm 129 and its third contact. armature and back contact .of relay 125. armature and front contact of relay 12c. conductor 12-10. arm 131 and its third contact. conductor 132. arm 20+ and its first contact. slow relay 205. leftarmaturc and back contact of relay 20S. conductor 207. conductor 208. arm itltl and its .first contact. magnet 20? to free pole of battery. "lhe selector brush shaft is thus given a movement in a primary direction to position a set of brushes 210. 211. 212-on the selector brush shaft in operative relation to the desired group ofoutgoing trunks. Rela) 205 being slow to release. maintains its armature attracted while impulses are being sent-to the magnet 203. and connects ground orcr armsjllfl and 2 17 t the escapcmaguet '21'fr of thesclcct'oi. which magnet releases its arms from position to position upon its doi ncrgization. in the well-knownmanner. When the si-mlcr-lifi reaches its normal position and the relay 125 is maintained energizcd. slow relay 205 la-conics docucrgized a fur ashort interval. and by retrzu-ting its armature. dci ncrgizcs magnet 215. which rcleascs'the si'dc switch into position. in position 2 magnet 215 is again energized over a secondary off-normal contact 216,

which opeuson the first secondary" step of the selector shaft. Arm 217 in position 2 connects an interrupter 218 to the se 'ndary stepping, magnet 219. The brushes. 10, 211, 212' are thus stepped over the multiples 213, 214, 235 of the selected group of; trunks. The multiple test terminals 235 of busy trunks are grounded, as will hereinafter appear. Consequently, magnet 215 is mainta ihed energized over test brush 212 and sudi grounded test terminals. When an ungrou-iitied test terminal 235 is reached, the escape magnet215 is decnergized and 'releases the side switch into position 3. Arm 217 in passing out of position 2, opens the circuit of magnet 219, stopping the brushes upon the seized trunk. In position 3, arm 220 connects the right grounded armature and front contact of relay 200 to themulti' plcs 235 of the seized trunk to cause the same to test busy to other testing selectors. \V hen the side sw itch-moves into position 3, p arms 209, 236 connect the conductors 208,

221 to the selecto' brushes 210, 211. Relay 301 at the connectorfl ig. 3) is thereupon energized over the following circuit: ground,

right armature a .id front contact of relay 200; arm 220, con luctor 222, brush 212. terminal 235, connector side switch arm 8 and its first contact, right armatureand back contact of connector release magnet 302,-;-

la v 301.-free pole of battery. Relay 301, by, attracting itslefit armature. inter-poses a break in the. ciicuit .of connector release magnet 302. am by attracting its right armature. connects the primary magnet 303 of the connector to the upper talking 0011- doctor 31?). The calling'party now operates his sender 128 to transmit the tens digit of the wanted line. Each time relay 125 retracts its armature. an impulse is sent. over the following path to magnet 3W3: grouiul. arm 12 and itsthird contact. armature and back contact of r slay 125, left armature and front contact of relay 12(1. conrluctor130,

a ri'n 131 and its t' ird contact. conductor 132,

arm 21H and its third contact. slow relay 205. left armature and back contactof relay eon, cmiductors' 207. 209. 11111120 and its third contact. brush 210.tcrminall2l3. conductors 315i. 316. arm 5, audits first cm ltact;

right armature and front contact of relay 11-5 ground. arl'uatu-c and front contact of re lay 205. cmnluctor 221. arm 23ti, brush-211. tcrn'nnal 214. coiuluctors 323. 324. arm (1 and its first contact. armature and. back' contact ofrelay 308. escape magnet 304 to free pole 13.0 i I ofhattcry. When thedial 128reaches its normal positlonand relay 125 is maintained energized, relay 205afterf a shortinterval becomes decnergized, and removes ground from the lower talking "conductor 221 whercupon'the escape magnet 304 releases the side switch into position 2.- In position 2, a rm4r. substitutes the secondary stepping mag-netSlO for the primary magnet 303 in the stepping circuit. The calling party non operates his dial totransmit the units digit of the wanted number. Each time the relay l 125. retracts its arlnatiu'e', an impulse is sent over the path just traced to conductor 316 (Fig 3), from whence it passes, by way of side. switch arms 5 and l in position 2, to magnet 310.; As before, relav 205 grounds the lower talking conductor 221, a'gai'n energizing the escape magnet 30%, the circuit being-thesame as that hereinbefore tracedfor' this magnet'to' conductor 324, from whence it passes by way of arm6 to such magnet. 'npara'llel with .magnet 304 a slow relay 33.0 is energized; Vhen the dial reaches its normal position, relay 125 is maintained energized, and when relay 205 retracts its armature, ground i sremoved from the lovyer talking conductor 221, whereupon magnet becomes 'denergized, releasing the side 30- switch into position 3. A busy line is indicated by reduced potential upon its j test I multiples 322 The relay .306 --is marginal and is not adapted to respondto such re glu'ced potential; If the. line is free, how- 1 ca er, full potential is present-upon multiples .1322 thereof. T

Assuniingthe line selected to be freeprea lay 306 energizes over, the following circuit; freepole ,of battery, cut-0E j relay 350 of;

the called line, terminal 322, brush 319, arm 3 and its third contact, both windings of relay 306 in Qseries, conductor 328, arm 8 and its :third contact, -te rminal 235, brush 212', conductor" 222, "arm 220 and "third contact, right armature and front:- contact e ir lr -y 200 ftqs f und- Rel y 3, ,7by' ,{I'a'ctng its leftbermatur'e, renders the se-.

econ,

H 'onduotorfwBgto ground ture and front contact of Slow relay 3.30 {is main 7 in -p a1;a' :lel; in this circuit,

generator 329 to the called line. -When the subscriber removes his receiver, relay 808 is energized, and in attracting-its armature, opens the circuit of magnet 304:, which, in denergizin g, releases the side switch into position' 4, in which arms 1 and 2 connect, conductors 315, 323 to connector. brushes 317 318, and arm 3 connects ground to test terminal 322. .Relay 330, 'ene'r ized in parallel with the escape magnet 3 4, being slow, maintains its armature attracted for an interval after arm 9 leaves its third osition. An'impulse'is thus transmitted rom round byway of the left armature and ront contact of relay 330, arm 10 a nd its fourth contactto the lower talking conductor 323,'terminal 214, br ush 211,"arm236- and its third "contact, conductor- 22 1, armature and backcontact of rela- 205, right winding of relay 206 to free p0 e" of battery. 3;, Relay 206 is momentarily energized by this, impulse, and in attracting-its right armature, energizes and denergizes the escape magnet 215, which releases the side switch into position 4. Arm 8 of the connector side switch in position 4' againconnects the grounded test conduc fil 222 to relay 301 before slow relay 330 decnergiz'eso In position 4, selector side switch arms 223, 224 connect the talking conductors 225, 226 'to .co'nductors 203, 221; thus completing the talkingcircuit, The 'called line battery'supply relay 206 isthen energized over the ca led line circuit, as'follows: free pole of battery, right winding of-relay206, armature and back contact of relay- 20 ,:cond11ctor 221-, arm 236, brush 211., terminal 214,-conductor .323, arm 2. and its fourth contact, brush 31 8, tenninal 321, line conductorv 325, through the telephonic apparatus at. the 05 called substation, conductor 326, terminal 320,,brush 317, arm 1 its fourth, con tact, conductor 315, terminal'2 l3 brush 210, mm 209" and-its fourth contact, conductor, 20S, arm 223, conductor 227, left- W 1 110 of relay ,2"6 to ground. VVhen I k switch moved f osition 3 to po to t e} -c0nnec t10n of reommunicatvl in, I

; substation A'fwill transnit'two impu se h-t ture and front contact of relay 126, armature and back contact of relay 125, arm 129 tracting its left armature, closes the low re-- sistance shunt about the cut-ofi' relay 120 to the test multiples 1.19, and by attracting its right armature, rounds the group multiples 101 and energizes relay 102. Relay 102, in attracting its right armature, grounds the starter wire 103 to start the next idle finder. This circuit is as follows,

assuming the finder of Fig. 1 to be the next idlerfinderr ground, right armature and front contact of relay 102, conductor 103, left armature and front contact of relay 109, out-starter wire 127, in-starter wire 139, right armature and back contact of relay 102 of the next idle finder, starter wire 103, left armature and back contact of relay 109, left armature and back contact of magnet 108,

arm 107 and its first contact; ari'nature andhack contact of primary magnet 106, magnet 100, free pole of battery. This finder is now given a primary and secondary movement to pick out the multiples 117, 118, 119 of the calling line on such finder as described; \Vhen the finder connects with such multiples, ground is applied to the cutoff relay 120 over side switch arm 180 of the special side switch associated with such finder. and a rm 122 and its third contact of the side switch (-oi'itrolling such finder, thus energizing the cut-off relay 120, which in attracting its armatures, deinergizes line relay 100. This latter relay in 'rctracting its left armature, removes the low resistance shunt from about the cut-off relay 120 to render the line non'calling in the other finders in which it appears, and in retract ing' its right ari'nature, removes ground from the group multiples 101 and dci nergizes relav 102. which restores the connection of the iii-starter wire to comluctm" 103. A relay 10-4 of the group to which the first tinder sci, belongs is energized in parallel with the primary and secondary magnets 100, 113; during the setting operation ust traced.

This relay removes-the control of relay 102 from its group during such setting 'operation ti'iwprcwnt lIli('I'f0l'0ll(50. The calling party at substation A now operates his dial HR in set the first selector, associated with the second finder. to pick out a connector, which is then set upon the terminals oi the third line. This operation is similar to that side switch arm 180 from posit on to position upon its dedescribed in netting up the first call. The parties may now converse. If, after talking, the panics desire to brin another party intotho connection, the calfing party i the s )ewill again transmit two impulses" to cial escape magnet 135 of the finder which.

last connected to his line and which is maintainlngithe same non-calling. This magnet then releases .ts armlSO to position 3 and renders the line calling and starts the next idle finder in search of multiples thereof, which finder, when it connects therewith, re-

moves the calling condition andfiirnishes I another outlet over which the calling subscriber co'ngec s with another party to bring him into the connection. 7

Upon the termination of the conversation,

the replacement of the calling partys receiver denergizs relays 125 of the finders connected to his circuit, which, in retracting their armatures, energize the release magnets 108 thereof to restore such finders, the circuit leading over the armature and back contact of rela vs 110, 126, 125 and the pri mary off-normal contact 134. Magnet 108 looks itself to ground at such contact and providesa circuit for relay 109 to hold the same operated to maintain the in-sta-rter wire 103 exterded to the next idle finder until the finder shown in restores, in case the called party hangs up his receiver first, thereby deenergizing relay 200. When the called parties hang up their receivers, the respective selectors and connectors are released as follows: relay 206 becomes dener gized, opening the circuit of Fig. 1 completely relay 200. W'hcn relay 200releases'it's right armature, release magnet 202 is energized over primary off-normal contact-230 to restore the selector, and ground is removed from conductor 222 leading to the'connector,

- causing the dt'e'nergizat-ion of relay 301,

which in retracting its left armature, energizes release magnet 302 over primary off-'- normal contact 331,'wl1ich restores the connector.

Referring now to Fig. 4, this view shows a modification of the invention wherein the cotiperation'of t 1e calling and called parties is necessary in (rder to bring a third party into the connect ion. Inthis case, when the parties desireto hrin connection, the mile party must 0 ierate his dial to transmit two impulses. T is causes the called supei visory relay 200 to decenergize twice, whereupon two impulses are sent over the. following path to operate the: spccialside switch 135: right armature and 1 back contact of relay 206,arm and its fourth contact, conductor 137, magnet 135, free pole of batt y. The escape magnet, in energizing and d :iinergizing twice, moves its side switch arm 180 into position 3, in which position ground IS removed from the cut-off relay 120, which, in, causing the energizatlon" another party into the L relay 100, starts another finder which picks up the calling line, as before. The calling party .can then, by operating his sender128, set-the selector associated with this finder onto a connector having access to. the wanted third party, and then set such connector upon suchpartys line. It will be noted that impulse conductor 132 in this modification is connected directly to magnet 205, instead of through side switch arm 201..

If the selected line is busy, test multiples 322 are grounded. Therefore relay 306 will not energize, and since the circuit of relay 330 is opened when arm 9 movesoff its secend contact, this relay, after .an interval,- releasesits left armature, removing ground from the circuit of relay 301. In position 3, the circuit for this relay 301, hereinbefore traced including test conductor 222, is

opened at side switch arm 8. Consequently, relay 301'retracts its armatures, and its right armature, in closing its-back Contact, closes the circuit of release magnet 302 as follows:

free pole of battery, magnet 302, left armature and back contact of relay 301, primary off-normal contact 331 to ground; Magnet 302 releases the connector and, in attracting its left armature, locks itself to the grounded test wire 222 as follows: free pole of battery, magnet 302, left armature and back contact of relay 301, contact 307 closed before contact 331 opens, resistance 340, right armature and front contact of magnet 302, arm Sand its first contact, terminal 235, brush 212, conductor 222, arm 220 to ground at the right armature and front contact of relay 200,

and closes the following circuit from a busy machine.332 to indicate to the calling party that the desired line is busy: busy tone apparatus 332, left armature and front contact of magnet 302, lower talking conductor 323, terminal 21* brush 211, arm 236 and its third contact, armature and back contact of relay 205, right winding of relay 206 to free pole of battery. This tone is transmitted inductively by the windings of relay 206 to the calling party over the following path v ground, left winding of relay 206, conductors 227, arm 123 and its third con tact, brush 111, terminal 117, the telephonic apparatus at substation A, terminal 118, brush 115, arm 12+ and its third contact, conductor 133, right winding of relay 125 to free pole of. battery. \V hen the calling party replaces his receiver, relay 125 is deenergized, and, by releasing its armature, closes the finder release circuit as hereinbefore traced. Relay 125, in det nergizing, releases relay 126, which, in retracting its right armature, removes ground from slow relay 200. This relay, lIl retracting its right armature, energizes selector release magnet- 202, whereupon the selector restores. The release magnetsof the finder, selector and connector restore the side switch arms in the retracts its armature, an impulse is sent over well-known manner. Arm 220, in restoring,

removes ground from conductor 222, whereupon release magnet '302 becomes de'nerof counting relays a, b is associated with the finder. When the first selector side switch moves into position 4 upon the response of the called party, the first primaryrelay a is connected over conductor 137 with the backcontact of the stepping relay 125.' In thigs.

circuit arrangement, when the parties desire to brln a third party into the connection,

the calling party operates his sender 128 to transmit four impulses. These impulses op- 'erate and lock up relays a, b in succesio'n until relay a is reached. This relay, in attracting its armature, opens the circuitofcut-off relay 120, which, in retracting its armatures, re-connects the line relay-100 to the calling line. energizes and causes a second finder to hunt for and connect with the calling line, as a1 ready described. Considered more in detail, the circuit for operating the cut-off relay 120, completed in position 4 of the selector side switch, leads over the right armature and back contact of relay at. When the connection is established and the calling partyat'substation A operates his sender 128 to transmit four impulses, stepping relay 12:3 retracts its armature for each interruption of the line circuit. The first retraction causes an im ulse to pass over the following path to the rst relay a: i

Free pole of battery, relay a, armature and back contact of relay 1), conductor 1'37, side switch arm 201 and its fourth contact, conductor 132, side switch -arm' 131 and its third contact, conductor 130, left-armature and front contact of relay 126, left armature and back contact of relay 125, arm 129 to ground. Relay a, in attracting its armature, prepares a locking circuit for itself and relay 1) leading to ground at the armature and back contact of relay 0, which circuit is closed when relay 125 again energizes and removes the shunt from about such relay b. Relay b, in energizing, as relay I25 attracts its'armature, prepares a circuit for relav a. When the stepping relay 125 next the path traced to conductor 137, from whence it passesby way of ,armature and front contact of relay b, armature and back The line relay thereupon contact of relay a free pole of battery.

Relay a, in attracting its ri ht arm'ature,

locks itself in series with re ay b, which prepares a circuit for relay a when relay next energizes. tion' of the armature of stepping relay 125, animpulse' is sent over the circuit traced to Upon the next rctracecirer by the Calling Belay I conductor 137, from whence it passes over the urlilatures and front contacts of relaye b,

b to the armature and haek contact of relay b relay a to free poi'eof battery. Bela a thereupon locks itself up in series wi't relay b. Relay b? energizes when relay 125 next energizes'and prepares a circuit for relay a, (hen the stepping rla y 125 next retracts its armature, an impul e is se'nt ever the path tracedto conductor 137', from whence it iassee over armetures and front contacts relays I) b and b to relay m. Relay a thereupon locks itself up in series with relay to ground at the armature and li ac'lc contact oi't'relay 0. Relay" (i","iIi' at tiactinggfi'ts left armature, opens the circuit of the-eu-t-ofi' relay, 120, which, in retracting its armature; reeonneets the line relay to t-hc'calling line circuit. The line relay thereupon ener izes with the results hereinbefore stated; wghcn the second finder. connects with the calling l'i'neyground is supplied to operate c'ut-ofl-Trelay over side switch arm 122 and the lefbavmature and back Contact of a relay corresponding to a Tlie relays a 'b, etc., remain locked up during the coniaera'tion. Upon'ihe replacement of the reparty, relay 125 de energizes and opens the circuit of relay 126 "ofcac'zh of the fiuclere. B elay 126 being slow mieleasemn pullee is transmitted over the ruiitfto relay (n'grouml, arurlQt) contact; armature and back realit 125 left ari'natine and front contact of contact ofrel'ay- 126; conductor 1'30; arm 131 angl. it$-tliird cont-act, concluct'or 132, arm

-204and its fourth coutact-, conductor 137.,

'l ftfli rmatu 'es and front contacts of relays b relay c,--to free :pole. of battery; in attracting itea r'lature, opens the 100i ng circuit of relays a 7); ct(., which 'therefifion kestore. Iii'thecircuit "arrange; ment ofFig-bfi, as in the circuit arrangeln cnt. of Fig. 1, the calling, subscrihclflan, if (led itcau'l'li'part-y into the connew ra'nainitting fem: impulses to tere a nf'jaiulli as. "i atcii with decomln t mewane-t. with the calling;

mjnglit will be seen that i ioi-rln-ovirleaiil imple and l of ll 1 11, an additional party or "m'ret with prone-ton: for-causing: eh partiesito1.test busy a'fler sing all the en itches and ed in the nnection upon in circuit imeen fm; enabling the. parties to to-thelronnection'; and for its circuithcing-opened as arin -1 S0 'nioves from position to position 4, thisiiiterral is not lon enough to hold, i-elay'lflieiier gized unti .a second finder connects with the ('allin' line, and referring to Fig. 5, if more than our impulue's are sent, the relay 0 will energize on the ifth impulse and reconnect ground to the cut-off relay. Thus, the privilege of setting up connectiom of this character may be ItStIiCtQd to certain parties, and the number Of the series of impulses required to start a second finder may be changed from ti ne to time by merely altering the connection of ground to the special side switch contacts and to the counting relays.

What is'cclaim'ed is: a

1; In 'a telephone exchange system, the

combination with a ('allingvantl a eall tl'l aiu'omati'r switching ineanSsa sei liie eiatcd'nith s (l callingiine adapt ii ti'ol saidswitchimjjiieans-i'toesta lflie a g sa-ill'li'nes hereby the i may o-p'erat automatic su toinclude Salli-third line in sate cu'i't means for causi saidiin busy, and lliAlI1S -f(i1" an Said switching n n 7 o v In a tale ll 1e text-image sjvst V a 'mtllinga'nri'a t i a 2'. In a telephone exchang system, the

. 4. a" telephone; exchangesystemf-the combination with av calling and aZcal-led has,

a senderinsaid'callin dine, a train create to be set thereby to ,uponthe'receipt of a predetermined number of impulses, whereupon the remaining swi es ma be operated',.by said sender to 16 brlug-saidt ird' line into the connection.

5. In atelephone exchange system, the combination mike calling and a called-line,

' "i s ndsin' sa dcelfinglinmtrain of autom ne switches adaptedto b set thereby j to. i n tsi dz s and, a thirsl' in ii f vanothertrain of automatic switches ad to. i'ntei'connect sa id third line withsai d im terconnected lines el a nd an electromagnetic switch jdapted'to beoperated bysaid sender after "the'calling and called lines are interconnected to associate the first switch of said second train of switches with said calling line upon the-receipt of a predetermined number of impulses, whereby said sender may operate the remaining switches of the train to bringa third partyinto the connection. j' H I I V 6; Inn telephone exchange= system, the combination witha callin'g'and a call'e'd line, a line relay, a cubofl :nelay and a sender for, said j'callin'g line nu'merical and non-numerical automatic switchesggsaid linejrelay being tion of aeall'to cau e adapted upon the initia' sai nonnum cul switbhes'to con- 40 'n' the calh ine nd erativgly m: vneuf' a .umericc, swtcnes'with Said sender, whemby sai'd sender may -con-' {ml the same to interconnect said'glines; and

a switch ass ciated With-"the witchiconiiected-to the-call I ,switcl upon receipt of nn'ect said third'line in'circ'uit with ,said I derth'e .contro i d l e, i- :1 sesame-Swat ated with said. line finderincluding a control andmeans controlled by said line relay. force all e c m with th all? 10 Inc telephone;

c'eipt of u-predetermined number of impulses .froin said sender to openthe circuit of said cut-01f relay to permit said line relay to energize to cause another non-numerical switch to connect with the calling line, said a lesser number ,of impulses failing to open'said cut-off relay circuit and u on receipt of a greater number i-eclosing said circuit. before a second finder n. rea ch the calling line. l i 5 8. In a telepho'ne exchange system, the combination with a calling and a called line, afline. and cut-off relay for said'callin'g line, automatic switches including line finders means adapted upon the energization of-said' 30 line relay upon the initiation-fol. a call for causin one of said finderssto connect with the ca ing line, a circuit for operatingsaid' cut-01f relay completed'by said finder, a special switch controlling the circuit of said cut-oft relay, a sender in .said calling line adapted to set u a c'onnec'tion'with said called line over said finder by means of said automatic switches, and after the completion .of such connection, to cause said special switch to deenergize said cu-t-ofi 'relay to permit said line" relay to reinergize, andmeans'operated thereb to cause, a second finder to connect with t e calling line.

9. In a telephone exchangefsystem, the combination with a calling'and called line, a

, line relay,'a cut ofl relay for said calling line adapted when energized to disconnect line'rela'y fromsaid line, automatic switches 1 including line finders,- adapted upon the energiz'ation of said line relayupon the. initiation of a-"callfifori causi ing one ofjsaitd finder. switches to connect with the calling line', acircuit for-operating said 1 cutoifrela rclosedwhen'said fin'de with-said] nega stepping relay :1 lof said sender to impulses to said automatic .swit'e feet connection with said called, 1

magnet, said wit hhaying an arm-control: ling the circuit of said-ibutofi' 1-e1a ,-.m ns for connecting said control magnetite: tact of said stepping relay aftertliei-coin lion Of a, connection, said switch when sited said stepping, relay beingia e cirouitof said cut-o la ee 1 3: 3" lfgllile g l eiiohange a sender, means with the calling line, a circuit for operating Said cut-01f relay closed when said finder connects with said line, a: stepping relay. adapted under the control of said sender to transnnt m'ipulses to saulautomaticswitches to effect connection with said called line, and

' combination. Wallisilin and called lines,

Ia third line of a s)ecial'sitlesu'itchassociated with said line findehincluding a control magnet, said switch having an arm controlling the circuit of cutoff relay, means for conl'iecting'saicl control magnet to a con.-

tact of said stepping relay after the comple tion of a connection, said switch when 0perated-by said stepping relay being adapted to open the circuit of said cut-off relay to cause the energization of the calling line relay, and means col'ltrolled by the energiza tion of said. line relay for causing a second finder to connect with the calling line. I

.11. In a telephone exchange system, the

:1. km relay and a cut-off relay for said call- ",ing line, the latterwhen energized disconmeeting theline relay from the line, automatic switches Including line finders, side switches therefor, a sender, means adapted upon the energization of said line relay upon .the initiation of a call for causingone of said finder switches to connect with the call- 1n line, a circuit for operating said cut-ofl closed when said finder connects with aahdline, .a stepping relay adapted under the i bontrol of said sender to transmit iinpulses to said automatic switches to effect connection with said called line, and a third line, of a special side switch associated with said line 1 finders having a control magnet'adapted to 'be connected to a contact of said stepping re- ,lay over 'a selector side switch arm after the arm controlling said cut-ofi relay circuit,

said switch when onerated by said stepping A relay bei adapted to open the circuit of said cut-o re lay to cause the energization of the calling line relay, and means controlled by the energization of said line relay for causing a second finder to connect with the calling line.

12 In a telephone exchange system, the combination with a calling and called line, a line relay, a cut-off relay for said calling line adapted whet. energized to disconnect said .line relay from said line, automatic'switches including line finders, side switches therefor, a sender, means adapted upon the energize.- .tion of said line relay upon the initiation of a call .for causng one of said'finder switches to. connect with the calling line, a circuit for operating. saic', cut-off relay closed by said finder, a stepping relay adapted under the control of said sender to transmit impulses to said automaticswltches to efl'ect conection. with said calling line, and a third line] i by operating his sender, causes said special side switch to dei nergize the calling line cutoff relay to permit the energizatlon of the line relay, which in energizing, causesan- 1 other finder to connect with the calling line.

In witness whereof, I hereunto subscribe my namethis 29th dayof April A. D., 1916,

ARTHUR B. SPERRY. 

